Underwater sonar array

Abstract

A sonar array connected to a data unit includes a substantial number of hydrophone units distributed along a small diameter cable having a substantial number of connecting wires, a center strength member and a tough polyurethane jacket. The hydrophone units each include a strong metal bracket bifurcated at each end and fastened to the strength member. A generally cylindrical hydrophone member is fastened to the bracket as is a circuit board including a preamplifier and the entire unit is sealed with paraxylene resin and then molded into a smooth generally cylindrical unit which is tapered at the ends and sealed to adjacent parts of the cable jacket. To minimize the cross-sectional area and the effects of cross currents, the cable is composed of a plurality of interconnected sections, each of which is of smaller cross-section and carries fewer conductors than the section next closer to the data unit. To assure that the array extends substantially vertically from the data unit, either a weight or a float is fastened to the cable at the end remote from the data unit.

We claim: 
     
       1. In an underwater sonar system including a data collection and instrumentation unit A hydrophone array extending vertically from said data and instrumentation unit including an elongated cable containing a center strength member, a plurality of insulated conducting wires, and an external jacket of durable plastic material;   a substantial number of hydrophone units connected to said cable, said hydrophone units each including a bracket member having a pair of longitudinally extending flat parts and a socket part at each end of said flat parts including longitudinally aligned slots operatively connected to said strength member, a hydrophone and a circuit board attached to said bracket member, some of said conducting wires being connected to said circuit board and said hydrophone being connected to said circuit board, said hydrophone units having a coating of paraxylene resin and an external potting coat of polyurethane which is smoothly tapered at each end of said hydrophone units from said brackets to said cable;   said cable including a plurality of sections of progressively smaller diameter attached together with the largest diameter section containing the most conducting wires attached to said data and instrumentation unit, the next smaller diameter cable section having fewer conductive wires being attached to the largest section, and with additional sections progressively becoming smaller in diameter and having fewer conducting wires with the last section having the smallest diameter and the fewest conducting wires.   
     
     
       2. A sonar system as claimed in claim 1 wherein means is attached to the end of said cable remote from said data and instrumentation unit exerting a force tending to hold said cable in a vertical attitude. 
     
     
       3. A sonar system as claimed in claim 2 wherein said means comprises a weight in the form of an oblate spheroid. 
     
     
       4. A sonar system as claimed in claim 2 wherein said means is a float. 
     
     
       5. A sonar system as claimed in claim 2 wherein a tethering line and anchor are fastened to said data and instrumentation unit, said tethering line being anchored to the ocean bottom, and said cable is attached to said data and instrumentation unit at a significant distance from the point of attachment of said tethering line. 
     
     
       6. A sonar array as claimed in claim 5 wherein said circuit board includes a preamplifier. 
     
     
       7. A sonar system as claimed in claim 1 wherein said center strength member has a portion removed at the location of each of said brackets, a fitting with a ball at the end is fastened to the resulting cable ends and said fittings are wedged in said slots in said brackets with said balls behind said slots. 
     
     
       8. A sonar array for attachment to an underwater data collection and instrumentation unit including a cable having a center strength member, a plurality of insulated conducting wires and an external jacket, a plurality of hydrophone units attached to said cable at desired intervals, and means at the end of said cable to tend to cause said cable to be deployed in a substantially vertical attitude; said hydrophone units each including a bracket member having a pair of longitudinally extending flat parts and a socket part at each end of said flat parts attached to said strength member, a hydrophone attached to said bracket member, electronic circuit means attached to said bracket member and connected to said hydrophone, with some of said conducting wirs being connected to said electronic circuit means;   said cable being formed of a plurality of sections of graduated diameters and numbers of conducting wires, with the section of greatest diameter and numbers of conducting wires being connected closest to said data collection and instrumentation unit and the section of smallest diameter and least number of conducting wires being connected at the greatest distance from said data collection and instrumentation unit.   
     
     
       9. A sonar array as claimed in claim 8 wherein said means at the end of said cable is a weight in the form of an oblate spheroid having its smallest projected area aligned generally perpendicular to said array. 
     
     
       10. A sonar array as claimed in claim 8 wherein said array includes at least approximately thirty-two hydrophones and said cable is formed of at least four sections of graduated diameters. 
     
     
       11. A sonar array as claimed in claim 8 wherein said hydrophone units are coated with paraxylene resin and enclosed in a molded cover of polyurethane. 
     
     
       12. A sonar array as claimed in claim 11 wherein said data collection and instrumentation unit is tethered to the ocean bottom by means of an anchor and a line and the point of attachment of said array to said data and instrumentation unit is significantly spaced from the point of attachment of said line.